CENTRAL PATHWAY OF PHOTIC REFLEX MYOCLONUS

Direct, new evidence for the cortical origin of photic reflex myoclonu s in a patient with ''posterior cortical atrophy'' is provided. Photic stimulation elicited myoclonic jerks in the right upper limb muscles. An (H2O)-O-15-PET activation study with photic stimulation showed inc reased regional cerebral blood flow not only in both striate cortices but in the left premotor and primary motor areas as well. Transcranial magnetic stimulation over the area of the left occipital cortex elici ted motor evoked potentials in the right upper limb muscles. It is con cluded that in the central pathway of photic reflex myoclonus the cont ralateral occipital cortex is activated first, then the impulses propa gate intrahemispherically to the primary motor cortex, to elicit myocl onic jerks.